This application is related to and claims priority from Japanese Patent Applications No. Hei. 10-330986 filed on Nov. 20, 1998, and No. Hei. 10-331619 filed on Nov. 20, 1998, the contents of which are hereby incorporated by reference.
1. Field of the Invention
The present invention relates to a cooling device for cooling a heat-generating member by boiling and condensing refrigerant.
2. Description of Related Art
In a conventional cooling device described in JP-A-9-205167, refrigerant in a refrigerant tank is boiled by heat from a heat-generating member, and gas refrigerant from the refrigerant tank is condensed in a radiator. Further, a liquid-refrigerant returning passage is provided in a straight line within the refrigerant tank so that condensed liquid refrigerant from the radiator is prevented from interfering with gas refrigerant boiled in the refrigerant tank by heat from the heat-generating member. However, when the cooling device is used for cooling a computer chip and has a small size, it is difficult to form the liquid-refrigerant returning passage into a straight line around a boiling space of the refrigerant tank, because an attachment hole for attaching the heat-generating member such as the computer chip is necessary to be provided in the refrigerant tank around the boiling space. Further, for stably circulating refrigerant between the refrigerant tank and the radiator, the liquid-refrigerant returning passage is necessary to have a flow resistance larger than that in a gas-refrigerant passage from the refrigerant tank to the radiator.
On the other hand, in the conventional cooling device, the arrangement positions of the refrigerant tank and the radiator are restricted in a vertical direction so that necessary radiating performance is obtained. Therefore, it is impossible for the cooling device to be vertically reversely used.
In view of the foregoing problems, it is an object of the present invention to provide a cooling device boiling and condensing refrigerant, which has a sufficient cooling performance even when being vertically reversely used.
It is an another object of the present invention to provide a cooling device boiling and condensing refrigerant, in which a liquid-refrigerant returning passage is provided in a refrigerant tank to have a resistance portion generating a flow resistance.
It is a further another object of the present invention to provide a cooling device boiling and condensing refrigerant, in which a liquid-refrigerant returning passage is provided without interfering with an attachment structure of a heat-generating member.
According to a first aspect of the present invention, a cooling device includes a refrigerant tank having a boiling space in which a part of liquid refrigerant is boiled and vaporized to gas refrigerant by absorbing heat from a heat-generating member, and first and second radiators for cooling and condensing gas refrigerant from the boiling space by performing heat exchange with outside fluid passing through the first and second radiators. The boiling space of the refrigerant tank has first and second space parts defined by a surface of the liquid refrigerant, the first radiator is connected to the refrigerant tank to communicate with the first space part of the boiling space, and the second radiator is connected to the refrigerant tank to communicate with the second space part of the boiling space. Thus, any one of the first and second radiators always communicates with a gas-refrigerant space upper than the liquid refrigerant surface within the refrigerant tank, and the other one thereof always communicates with a liquid refrigerant space lower than the liquid refrigerant surface. As a result, even when the cooling device is used in a vertically reversed state, sufficient radiating performance of the cooling device can be proposed.
Preferably, the first radiator and the second radiator communicate with each other through a communication passage. Therefore, refrigerant having been cooled and condensed in any one of the first and second radiators, disposed at an upper side, is further cooled and condensed in the other one of the first and second radiators. Thus, radiating performance of the cooling device is further improved while the size of the cooling device is reduced.
Preferably, the first and second radiators are disposed in such a manner that any one of the first and second radiators positioned at an upper side in the vertical direction is inclined relative to a horizontal direction to be readily introduce liquid refrigerant into the communication passage, during a normal state and a reversed state. Therefore, it prevents refrigerant from staying in the radiator positioned at the upper side, and refrigerant-circulating performance of the cooling device is improved.
According to a second aspect of the present invention, a cooling device includes a refrigerant tank having a boiling space in which a part of liquid refrigerant is boiled and vaporized to gas refrigerant by absorbing heat from the heat-generating member, a radiator for cooling gas refrigerant from the refrigerant tank. The radiator has a first header into which gas refrigerant from the boiling space flows, a plurality of tubes in which gas refrigerant from the first header is cooled and condensed by performing heat exchange with outside fluid passing through the radiator, and a second header through which liquid refrigerant condensed in the tubes returns to the refrigerant tank. The refrigerant tank has a gas refrigerant outlet for introducing gas refrigerant from the boiling space into the first header, and a liquid-refrigerant returning passage through which liquid refrigerant from the second header of the radiator is introduced into a bottom side of the boiling space. In the cooling device, the liquid-refrigerant returning passage is provided at a side of the boiling space, and has a resistance portion at which a flow resistant of liquid refrigerant flowing through the liquid-refrigerant returning passage is increased. Thus, gas refrigerant preferentially flows through the gas refrigerant outlet as compared with the condensed liquid refrigerant flowing through the liquid-refrigerant returning passage. As the resistance portion, a bent portion or a throttle is provided in the liquid-refrigerant returning passage.
When the bent portion is provided in the liquid-refrigerant returning passage, an attachment structure for attaching a heat-generating member onto the refrigerant tank can be provided in a space obtained due to the bent portion. Therefore, the liquid-refrigerant returning passage is provided without interfering with the attachment structure of the heat-generating member.